1. Field of the Invention
The present invention relates to a pipe joint for connecting a pipe hermetically to a fluid pressure device.
2. Description of the Related Art
One conventional pipe joint of synthetic resin disclosed in Japanese utility model publication No. 7-20471, for example, is shown in FIG. 5 of the accompanying drawings.
As shown in FIG. 5, the known pipe joint of synthetic resin, generally designated by the reference numeral 1, has a cylindrical joint body 2 and an inner ring 4 inserted in a hole defined in the cylindrical joint body 2 and force-fitted in an end of a pipe 3. The cylindrical joint body 2 has an externally threaded end 5 in which the inner ring 4 is inserted. A pusher ring 7 has an internally threaded end 6 which is threaded over the externally threaded end 5. The pipe 3 extends axially through the pusher ring 7 and is axially engaged by the pusher ring 7.
The inner ring 4 has an inner end held against the inner end of the hole in the cylindrical joint body 2, providing a seal region 8. The seal region 8 is firmly pressed by the inner ring 4 which is pushed axially inwardly by the pipe 3 that is forcibly axially pressed by the pusher ring 7, thereby firming sealing the passages in the cylindrical joint body 2 and the pipe 3 against leakage.
Each of the externally threaded end 5 and the internally threaded end 6 which are held in threaded engagement to hold the pusher ring 7 on the cylindrical joint body 2 has small screw teeth of triangular cross section. When heated by a fluid flowing through the pipe 3, the pusher ring 7 tends to be loosened on the cylindrical joint body 2, damaging the seal between the cylindrical joint body 2 and the pipe 3.
There has been a demand in the art for increasing the sealing capability of the pipe joint 2 of synthetic resin.